Photographic materials producing a color change by reacting a metal salt with tetrahydroquinoline



United States Patent 3,397,983 PHOTOGRAPHIC MATERIALS PRODUCING A COLOR CHANGE BY REACTING A METAL SALT WITH TETRAHYDROQUINOLINE Louis Maria De Haes, Edegem, and Jozef Frans Willems,

Wilrijk-Antwerp, Belgium, assignors to Gevaert Photo- Producten N.V., Mortsel, Belgium, a company of Belgium No Drawing. Continuation of application Ser. No. 174,246, Feb. 19, 1962. This application Jan. 31, 1967, Ser. No. 613,037 Claims priority, application Netherlands, Feb. 17, 1961, 261,381; Feb. 6, 1962, 274,437, 274,438 15 Claims. (Cl. 96-29) This invention relates to a new photographic material which can be used for the manufacture of photographic images by a dry process.

This application is a continuation of Ser. No. 174,246 filed Feb. 19, 1962.

According to a previous proposal of the applicant (the Belgian patent application registered under Number 609,- 057) a light-sensitive material comprising a silver halide emulsion layer and a 3-pyrazolidone derivative after image-wise exposure can be developed by means of heat. On the exposed areas 3-pyrazolidone derivative is consumed during development, whereas on the unexposed areas unreacted 3-pyrazolidone derivative is left.

According to one of the embodiments of the cited Belgian patent application, the developed light-sensitive material is pressed onto an image-receiving material under the supply of heat whereby the unused 3-pyrazolidone derivative on the unexposed areas ditfuses from the developed material to the receiving layer of the image-receiving material containing silver salts, forming in this way by the reducing activity of the 3-pyrazolidone derivative a silver image.

According to the present invention a process has been found for producing photographic images by heat-development, wherein a photographic material, comprising a silver halide emulsion layer, a 3-pyrazolidone derivative and 8-hydroxy-1,2,3,4-tetrahydroquino1ine is subjected to a heat treatment, after or during exposure to an object to be reproduced.

The photographic light-sensitive material used in carrying out the process according to the present invention comprises, as stated hereinbefore, besides the 8-hydroxy- 1,2,3,4-tetrahydroquinoline, a 3-pyrazolidone compound, preferably a 3-pyrazolidone compound corresponding to the following general formula:

wherein:

R represents an aryl group or a substituted aryl group, R represents a hydrogen atom or an acyl group such as an acetyl group, and each of R R R and R (equal or different) represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group.

The following products corresponding to-the general formula appeared from the experiments to give particularly good results:

'1-phenyl-3 -pyrazolidone l-(m-tolyl)-3 -pyrazolidone 3,397,983 Patented Aug. 20, 1968 1-phenyl-2-acetyl-3-pyrazolidone 1-phenyl-4-methyl-3-pyrazolidone 1-phenyl-5-methyl-3-pyrazolidone l-phenyl-4,4-dimethyl-3 -pyrazolidone l-phenyl-5,5-dimethyl-3 -pyrazolidone 1,5 -diphenyl-3-pyrazolidone l-(m-tolyl)-5-phenyl-3-pyrazolidone 1-( p-toly1)-5-phenyl-3 -pyrazolidone.

A third developing compound which may be incorporated in at least one of the layers composing the lightsensitive material according to this invention, is pyrogallol.

It may be noticed that all kinds of gelatino silver halide emulsions namely: gelatino silver chloride, gelatino silver chloro-bromide, gelatino silver bromide, gelatino silver bromo-iodide and gelatino silver chloro-bromo-iodide emulsions, are suited for being used according to this invention.

The light-sensitive material generally contains from about 0.3 to about 2 g. of silver under the form of silver halide per sq. m.

Each of the above mentioned developing compounds, can be incorporated in any of the layers composing the light-sensitive material e.g. in the light-sensitive emulsion layer, in the support itself, but preferably in a waterpermeable layer which is situated on the same side of the support as the light-sensitive emulsion layer.

. The developing compounds are in general incorporated in such quantities that 1 sq. m. of light-sensitive material contains: from 0.5 to 5 g. of a 3-pyrazolidone derivative, preferably from 1 to 2 g.; from 0.25 to 2.5 g. of 8-hydroxy-l,2,3,4-tetrahydroquinoline, preferably from 0.5 to 1.5 g. and from 0.5 to 5 g. of pyrogallol, preferably from 1 to 2 g.

The silver halide emulsion layer and/or a water-permeable layer can also contain compounds which on heating liberate water, or which are-hydrolyzed whilst liberating alkali, e.g. alkali and earth-alkali acetates, sodium citrate, sodium benzoate, sodium formate, sodium stearate, potassium palmitate and calcium lactate. These compounds improve the heat-developability.

The use of hydrophilic plasticizers e.g. glycerol, caprolactam, polyethylene glycols and the like, also results into an improvement of the heat-developability. Also in this kind of emulsions the image quality can be improved by incorporating into the emulsion compounds which favourably influence the image tone e.g. l-phenyl-S-mercaptotetrazole or similar products, which are described. in British patent specification 561,875 and Belgian patent specification 502,525.

According to this invention a photographic light-sensitive material, as described above, is exposed to an original and thermally developed, whereupon a suitable image is obtained.

The developing lasts mostly from about 1 to about 20 sec. dependent on the temperature which may vary from to 200 C. v

The amount of heat which is necessary for the development may be applied in various ways. So the silver halide emulsion can be developed by conduction, by contacting it with heated plates or rollers, by placing it between two capacitor plates which are subjected to a high frequency field, or'by subjecting it to the Joule effect. The silver halide emulsion can also be developed by convection e.g. by contacting it with a directed warm gas. stream. For this purpose e.g. warm air or steam may be used. Furthermore the silver halide emulsion can also be developed by heat radiation. The use of infrared radiation sources is especially suited therefor, not only because they have an intensive developing power, but also because they enable simultaneously exposure and development in a very short time e.g. a fraction of a second. By infrared radiation sources those radiation sources are understood of which most of the radiated energy waves possesses a wave-length of to 10' cm. In this way it is possible to contact a light-sensitive material, prepared according to this invention, with a film negative and to move it along a light-source which is rich in infrared radiations so as to obtain immediately a very strong positive image.

The density as well as the gradation of the images obtained according to this invetnion are excellent. After rinsing ad fixinng, the obtained density is also much better kept than it is the case with the most known developing compounds.

An especially interesting embodiment of this invention is the thermally manufacture of prints according to the diffusion transfer process. The material containing the image which is obtained according to one of the above described processes can thermally be brought into contact with an image-receiving material containing non-lightsensitive metal salts which are capable to form a coloured reaction product with 8-hydroxy-l,2,3,4-tetrahydroquinoline or with 8-hydroxy-1,2,3,4-tetrahydroquinoline and pyrogallol together.

Non-light-sensitive metal salts which are suited for being applied in the ditfusion-transfer process according to this invention are e.g.:

Iron salts such as ferrous chloride, ferric chloride or ferrous sulfate,

Copper salts such as cupric chloride,

Chromium salts such as potassium dichrornate, and

Cobalt salts such as cobaltous chloride.

These metal salts can simply be incorporated into a paper support which can serve as an image-receiving material, by immersing this support in an aqueous solution of that metal salt. The metal salt can also be incorprated into a water-permeable layer which is coated on the support. These metal salts are mostly present in such an amount that 1 sq. m. of image-receiving material contains from 1 to 10 g. preferably from 3 to 4 g. of these metal salts.

An image-receiving material can also be used which in addition to the non-light-sensitive metal salts also comprises as an essential component a thin layer of polyacrylamide, which makes possible to produce a negative and a positive image of an original by means of one single thermal development of the exposed light-sensitive material and of the image-receiving material pressed together.

The polyacrylamide is coated as one of the composing layers of the image-receiving material. Occasionally, the non-light-sensitive metal salts can also be coated from the polyacrylamide coating solution. In that case the polyacrylamide serves as a binding agent. Mostly the polyacrylamide is applied in amounts comprised between 2 g. and 8 g. per sq. m.

Examples of commercially available polyacrylamides are e.g.:

PAM 100, PAM 75, PAM 50 (trade-names for polyacrylamides marketed by American Cyanamid Company, New York, N.Y., U.S.A.). The viscosities of their 3% aqueous solutions at 25 C. are respectively of from 120 to 200 cp., from 60 to 100 cp. and from 35 to 50 cp.

Separan NP20, Separan NP10 (trade-names for a low and a high viscous polyacrylamide marketed by The Dow Chemical Company, Midland, Mich., U.S.A.).

For the application of the diffusion transfer process the image-wise exposed light-sensitive material is submitted for a short while to a heat-treatment according to one of the above described methods.

This preheated material is thermally contacted with the image-receiving material e.g. by means of heated rollers 4 or plates. Hereby the temperature may vary from about to about 200 C. and dependent on the used temperature the time needed for contacting varies from about 30 sec. to about 3 min.

During this treatment the developing compounds diffuse image-Wise to the image-receiving layer as to form with the non-light-sensitive metal salt present therein, a brown to black-coloured product. The obtained image is mostly brown. Only the reaction product of S-hydroxy-l, 2,3,4-tetrahydroquinoline and pyrogallol with an iron salt is black.

When using an image-receiving material which in addition to the non-light-sensitive metal salts also contains a thin layer of polyacrylamide it is possible to produce a negative and a positive image of the original in one single thermal development, by pressing the exposed light-sensitive material and the image-receiving material together; e.g. onto a heated plate.

The temperature at which this thermal development is carried out varies from about 80 to about 200 C. According to the temperature used the developing time varies from about 30 sec. to about 3 min.

The following examples illustrate the invention.

EXAMPLE 1 A light-sensitive material is manufactured as follows. Onto a photographic paper support of g./sq. m. a precoat is applied from a suspension of the following composition:

The pre-coat is applied in such a way that 1 l. of this suspension covers 10 sq. m. of paper.

After drying, an after-coat is applied from the following composition:

Ethanol cm. 1000 l-phenyl-3-pyrazolidone g 8-hydroxy-1,2,3,4-tetrahydroquinoline g 30 The after-coat is applied in such a way that l l. of this composition covers 20 sq. m. of paper.

The image-receiving material consists of a paper support of 90 g./sq. m. which is provided with a receiving layer. This receiving layer is applied by uniformally wetting one side of the paper support with a 10% aqueous ferrous chloride solution, whereupon the support is dried.

The light-sensitive material is reflectographically exposed to an original to be reproduced and thermally developed for 15 see. by contacting it with a plate heated at 80-200 C. A very suitable negative print of the original is obtained.

The receiving layer is then pressed for about 40 sec. upon the thermally developed light-sensitive layer by means of a plate heated at 80-200 C. whereupon both layers are separated from each other. A brown positive image of the original is apparent on the receiving layer of the image-receiving material.

EXAMPLE 2 A light-sensitive material is manufactured as follows. Onto a photographic paper support of 90 g./sq. m. a precoat is applied from a suspension of the following composition:

The pre-coat is applied in such a way that l l. of this suspension covers 20 sq. m. of paper.

After drying, an after-coat is applied from the following composition:

Ethanol cm. 1000 l-pheny1-3-pyrazolidone g 50 8-hydroxy-l,2,3,4-tetrahydroquinoline 30 Water cm. 100 Ferrous chloride g 5 PAM 75 (trade name), 5% aqueous solution cm. 200 Saponine, 12.5% aqueous solution ..cm. 0.5

This solution is applied in such a way that 1 liter covers 5 sq. m. of paper.

The light-sensitive material is refiectographically exposed to the original to be reproduced and then thermally developed together with a receiving material by pressing both materials for about 60 sec. against a 130 C. warm plate. After this treatment both materials are separated from each other. A brown positive image of the original is apparent in the image-receiving layer.

EXAMPLE 3 A light-sensitive material is manufactured as follows. Onto a paper support of 90 g./sq. m. is applied a precoat from a suspension of the following composition:

Cm. Silver chloride emulsion containing per kg. 30 g.

of silver 1000 Water 1000 Glycerol 100 Saponine, 12.5% aqueous solution 5 Formaldehyde, 40% aqueous solution 2 The pre-coat is applied in such a way that 1 l. of this composition covers 15 sq. m. of paper.

After drying, an after-coat is applied from the following composition:

Ethanol cm 1000 1-(m-tolyl)-3 -pyrazolidone ....g.... 100 S-hydroxy-l,2,3,4-tetrahydroquinoline g 30 Pyrogallol 1; L50

The after-coat is applied in such a way that 1 l. of this composition covers 20 sq. m. of paper.

The image-receiving material consists of a paper sup port of 90 g./ sq. m. onto which a receiving layer has been applied from the following solution:

Water cm. 100 Ferrous chloride g 5 PAM 75 (trade name), 5% aqueous solution cm. 200 Saponine, 12.5% aqueous solution cm. 0.5

6 We claim: I 1. A process for the photographic production of copies of an original to be copied which process comprises the steps of:

(l) Exposing with light to the original to be copied a light-sensitive material having at least one lightsensitive silver halide emulsion layer and having incorporated therein in effective contact with the silver halide of said emulsion layer a 3-pyrazolidone derivative and 8-hydroxy-l,2,3,4-tetrahydroquin0line in suflicient amounts to photographically develop said emulsion layer in the exposed areas thereof upon exposure of said material to heat and a compound adapted to release moisture on heating;

(2) Heating the light-sensitive material with the exposed emulsion thereon to a generally uniform temperature to develop in said layer a photographic image of said original; and

(3) While said emulsion layer is undergoing heat development according to step (2), contacting said layer with a face of an image-receiving material carrying a water-soluble salt of metal which salt does not undergo substantial coloration on exposure to light and in presence of moisture releases metal ions reactive with said 8-hydroxy-1,2,3,4-tetrahydroquinoline to produce a distinctive color change: to transfer said tetrahydroquinoline from the undeveloped areas of said emulsion layer onto said face and produce by reaction of said tetrahydroquinoline with said metal ions an image of said original of generally opposite gradation to photographic image of said original in said emulsion layer.

2. The method of claim 1 wherein said moisture releasing compound is a hydrophilic plasticizer.

3. The method of claim 1 wherein said light-sensitive material also has incorporated therein pyrogallol and said image-receiving material carries a metal salt also adapted to produce a colored reaction product by reaction with said pyrogallol.

4. The method of claim 1 wherein said 3-pyrazolidone derivative is a compound having the formula:

R is an aryl group,

R is selected from the group' consisting of a hydrogen atom and an acyl group, and each of R R R and R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

5. The method of claim 1 wherein said metal salt in said image-receiving material is an iron salt.

6. The method of claim 1 wherein said light-sensitive material is exposed to a radiation source emitting both actinic and infrared radiation to effect said exposing and heat developing steps concurrently.

7. The method of claim 1 wherein said light-sensitive material is heated to a temperature in the range of 200 C.

8. The method of claim 7 wherein said light-sensitive material is heated to said temperature while in contact with said image-receiving material.

9. A process for the photographic production of copies of an original to be copied which process comprises the steps of:

(1) Exposing with light to the original to be copied a light-sensitive material having at least one light-sensitive silver halide emulsion layer and having incorporated therein in etfective contact with the silver halide of said emulsion layer, a 3-pyrazo1idone derivative and 8-hydroxy-l,2,3,4-tetrahydroquinoline in sufiicient amounts to photographically develop said emulsion layer in the exposed areas thereof upon exposure of said material to heat and a com pound adapted to release moisture on heating;

(2) Heating the light-sensitive material with the exposed emulsion thereon to a generally uniform temperature to develop in said layer a photographic image of said original; and

(3) After said photographic image has been developed in said emulsion layer contacting said layer with the unused developing agents intact therein with a face of an image-receiving material carrying a water-soluble salt of metal which salt does not undergo substantial coloration is exposed to light and in presence of moisture releases metal ions reactive with said 8-hydroxy-1,2,3,4-tetrahydroquinoline to produce a distinctive color change and heating said emulsion layer while in contact with said image-receiving material face;

to transfer said tetrahydroquinoline from the undeveloped areas of said emulsion layer onto said face and produce by reaction of said tetrahydroquinoline with said metal ions an image of said original of generally opposite gradation to photographic image of said original in said emulsion layer.

10. The process of claim 9 wherein said moisturereleasing compound is a hydrophilic plasticizer.

11. The method of claim 9 wherein said light-sensitive material also has incorporated therein pyrogallol and said image-receiving material carries a metal salt also adapted to produce a colored reaction product by reaction with said pyrogallol.

12. The method of claim 9 wherein said 3-pyrazolidone derivative is a compound having the formula:

R is an aryl group.

R is selected from the group consisting of a hydrogen atom and an acyl group, and each of R R R and R is selected from the group consisting'of hydrogen atom, an alkyl group and an aryl group.

13. The method of claim 9 wherein said metal salt in said image-receiving material is an iron salt.

14. The method of claim 9 wherein said light-sensitive material is heated to a temperature in the range of 200 C.

15. The method of claim 9 wherein said 1ight-sensitive material is heated while in contact with said image-receiving material to a temperature in the range of 80- 200 C.

References Cited UNITED STATES PATENTS 2,596,978 5/1952 Burtner et a1. 9666.2 2,647,056 6/1953 Land 9629 2,663,656 12/1953 Miller et a1. l17-36.8' 2,855,299 10/1958 Rogers 9655 2,971,840 2/1961 Hayden et al. 9629 FOREIGN PATENTS 1,192,172 10/1959 France.

NORMAN G. TORCHIN, Primary Examiner,

J. P. BRAMMER, Assistant Examiner. 

1. A PROCESS FOR THE PHOTOGRAPHIC PRODUCTION OF COPIES OF AN ORIGINAL TO BE COPIED WHICH PROCESS COMPRISES THE STEPS OF: (1) EXPOSING WITH LIGHT TO THE ORIGINAL TO BE COPIED A LIGHT-SENSITIVE MATERIAL HAVING AT LEAST ONE LIGHTSENSITIVE SILVER HALIDE EMULSION LAYER AND HAVING INCORPORATED THEREIN IN EFFECTIVE CONTACT WITH THE SILVER HALIDE OF SAID EMULSION LAYER A 3-PYRAZOLIDONE DERIVATIVE AND 8-HYDROXY-1,2,3,4-TETRAHYDROQUINOLINE IN SUFFICIENT AMOUNTS TO PHOTOGRAPHICALLY DEVELOP SAID EMULSION LAYER IN THE EXPOSED AREAS THEREOF UPON EXPOSURE OF SAID MATERIAL TO HEAT AND A COMPOUND ADAPTED TO RELEASE MOISTURE ON HEATING; (2) HEATING THE LIGHT-SENSITIVE MATERIAL WITH THE EXPOSED EMULSION THEREON TO A GENERALLY UNIFORM TEMPERATURE TO DEVELOP IN SAID LAYER A PHOTOGRAPHIC IMAGE OF SAID ORIGINAL; AND (3) WHILE SAID EMULSION LAYER IS UNDERGOING HEAT DEVELOPMENT ACCORDING TO STEP (2), CONTACTING SAID LAYER WITH A FACE OF AN IMAGE-RECEIVING MATERIAL CARRYING A WATER-SOLUBLE SALT OF METAL WHICH SALT DOES NOT UNDERGO SUBSTANTIAL COLORATION ON EXPOSURE TO LIGHT AND IN PRESENCE OF MOISTURE RELEASSES METAL IONS REACTIVE WITH SAID 8-HYDROXY-1,2,3,4-TETRAHYDROQUINOLINE JTO PLRODUCE A DISTINCTIVE COLOR CHANGE: TO TRANSFER SAID TETRAHYDROQUINOLINE FROM THE UNDEVELOPED AREAS OF SAID EMULSION LAYER ONTO SAID FACE AND PRODUCE BY REACTION OF SAID TETRAHYDROQUINOLINE WITH SAID METAL IONS AN IMAGE OF SAID ORIGINAL OF GENERALLY OPPOSITE GRADATION TO PHOTOGRAPHIC IMAGE OF SAID ORIGINAL IN SAID EMULSION LAYER. 